Position retaining device

ABSTRACT

1,072,438. Adjustable seat backs. ANDERSON CO. Aug. 4, 1964 [July 25, 1963], No. 30976/64. Heading A4J. [Also in Division E2] A mechanical position-retaining device for chairs has a first member 110 for attachment to a chair base (189) Fig. 4 (not shown) and a second member 112 rectilinearly movable relative to the first member for attachment to a chair back (190) positionable with respect to the chair base. A nut 142 is fixedly carried by member 112 and has internal threading to co-operate with a threaded rod 138, the threading being relatively steep so that an axial force applied by the chair back rectilinearly between the members 110, 112 tends to rotate the rod 138. Such rotation is prevented by a brake consisting of a resilient coil 158, connected at one end 160 to a base part 116 of the member 110, surrounding and gripping a drum 144 connected to the threaded rod 138. The brake is releasable by engaging a squared end (164) Fig. 3 (not shown) of coil 158 by a shoulder (176) of a release member 166 to increase the inner diameter of the coil. A resilient friction washer 152 is disposed between the part 116 of the member 110 and the rotatable rod 138 to dampen rotation of the rod and hence the relative rectilinear movement of the members 110, 112.

Oct. 31, 1967 J. E. MARTENS 3,350,135

POSITION RETAINING DEVICE Original Filed July 25. 1963 N 9 7 go 83 @Wt oWI 0 y Q Q I: G '.v Q w 2 INVENTOR JACK E. MARTENS g WMAKL ATTORNEYSUnited States atent 3,350,135 POSITION RETAINING DEVICE Jack E. Martens,Bloomfield Hills, Micl1., assignor to The Anderson Company, acorporation of Indiana Continuation of applications Ser. No. 297,586,July 25,

1963, and Ser. No. 402,359, Oct. 7, 1964. This application Mar. 15,1966, Ser. No. 536,211

3 Claims. (Cl. 297-355) ABSTRACT OF THE DISCLOSURE This disclosure is toan extensible and retractable device for use with seats for holding apositionable back at the desired location. Its structure comprisesaxially extensible and retractable members, one provided with a nut andthe other with a rotatable screw, each having relatively steep threadingso that a force applied axially on the members tend to cause rotation ofthe screw and permits adjustment of the members. A brake is provided forselectively preventing rotation of the screw to retain the members in adesired position. A load bearing member, in contact with the screw, hasfrictional characteristics such that upon release of the brake, rotationof the screw remains substantially constant irrespective of the appliedaxial load to thereby dampen movement of the members.

This application is a continuation of application Ser. No. 297,586,filed July 25, 1963 and application Ser. No. 402,359, filed Oct. 7, 1964each application now abandoned.

This invention relates to a position-retaining device which isparticularly adapted for use on chairs having positionable backs.

In the prior art, a common type of seat-positioning device ishydraulically controlled or actuated. One of the characteristics of sucha device is that the hydraulic fluid acts as a cushion betweenrelatively movable parts thereof to dampen any sudden movement.

An object of this invention is to provide an improved position-retainingdevice.

Another object of this invention is to provide an improvedposition-retaining device employing movementdampening means.

Another object of this invention is to provide a positionretainingdevice with dampening means for controlling speed of ope-ration.

Other objects and advantages of the invention will become apparent afterthe description hereinafter set forth is considered in conjunction withthe drawing annexed hereto.

In the drawing:

FIGURE 1 is a partially cut-away side view of a position-retainingdevice;

FIGURE 2 is a cut-away view of one end of the mechanism showing analternate form;

FIGURE 3 is an exploded view of part of the elements of FIGURE 1; and

FIGURE 4 diagrammatically represents a seat with a positionable backempolying this type of position-retaining or holding device.

The position-retaining device, as disclosed in the various figures ofthe drawing, is for holding a load in compression. It will beappreciated that with a reversal of the threading on the screw and nut,or reversal of coil direction of the brake, the device may be rearrangedfor holding in tension.

FIGURE 4 shows the position-retaining device on a chair wherein it ismounted between a stationary base 189 and a positionable back rest 190.In this arrangement the position-retaining device is adapted to hold incompression but is submissive to a load in tension, such as caused by aseat occupant manually tilting the back rest 190 forward. It will beobvious that the use of such a device is not limited to a chair but mayfind use on beds or other reclining furniture as well. Use on recliningbacks for seats of busses, trains, airplanes or automobiles is believedobvious.

The device generally designated comprises a pair of telescoping membersand 112, respectively, which are adapted to be attached to relativelymovable parts or bodies of a chair or bed. Member 110 includes wingportions provided with holes 111 for anchoring by pins or bolts to oneof the above-mentioned movable portions, for example, the chair base asshown in FIGURE 4. Member 110 includes a cylindrical extension 114providing a recess for receiving a base 116 of an intermediate portion118. The intermediate portion includes sleeve extension 120. Thislast-mentioned extension is generally cylindrical and is adapted totelescopically receive an inner portion of member 112. Member 112 isgenerally cylindrical throughout its length and may terminate in anouter end of reduced diameter. This outer end is bifurcated and providedwith openings 124 to facilitate attachment by a pin to one of therelatively positionable bodies, for example, a tiltable back.

One or more pins 126 are received radially through the cylindrical wall114 and projecting into base 116 for holding members 110 and 118 fixedlyassembled in axial alignment.

Considering the disclosure of FIGURE 1, base 116 is provided with anaxially disposed cylindrical opening 128 which receives bearing bushing130 press-fitted therein. An axially disposed shoulder 132, disposedadjacent opening 128 within sleeve 120, will be more fully describedlater in the specification. The other end of base 116 is counterbored orotherwise provided with a recess 117 for receiving a bearing 134.

As can be seen in FIGURE 1, an elongate rod 138 includes a cylindricalportion 136 which is received through bushing 130 and bearing 134 forrotation about its longitudinal axis. The outer end of the rod isprovided with relatively steep threading 140 for cooperation with a nut142 which is fixedly carried by the inner end of member 112. The innerend of the rod is provided with threading and a lock nut 146 for fixedlyretaining thereon brake drum 144. Other means within the art may beemployed to secure the brake drum on the rod.

The junction between cylindrical portion 136 and threading 140 definesan axial shoulder 148 against which thrust collar 150 is fixedlypositioned. It will be noted that splines are provided on cylindricalportion 136 adjacent shoulder 148 so that collar 150 may be more readilysecured thereto. A washer 152 of Teflon or other material having similarcharacteristics is provided between shoulder 132 and collar 150. Teflonhas been found to have characteristics providing the necessaryresilience and coeflicient of friction with metal to provide the desireddampening and drag of rotation on rod 138. The surface of collar 150adjacent the Teflon washer is polished to a smooth surface relative tothat of shoulder 132. Therefore, relative movement is between washer 152and collar 150. The purpose of this feature will be more fully describedhereinafter.

Nut 142 previously referred to as fixedly carried by the inner end ofmember 112 has internal threading of relatively steep pitch forcooperating with the relatively steep pitch of threading 140 on rod 138.The outer peripheral surface of nut 142 is provided with threading forreception in a complementary threaded recess within the inner end ofmember 112. A pin or other means (not shown) may be used to preventrotation of the nut within the recess to prevent disassembly therefrom.

The outer end of rod 138 receives nut 154 and washer 156 thereon tolimit axial movement between members 110 and 112 and to prevent theirbecoming disassembled by reason of nut 142 travelling off the end ofthreading 140 on rod 138.

Brake means defined by a helically disposed resilient coil 158 surroundsdrum 144 for gripping engagement thereon. As shown in FIGURE 3, the coilis left-hand wound whereas the screw and nut contains right-handthreading. By this arrangement, the position-holding device is adaptedto resist great loads in compression but yield to loads in tensionapplied between members 110 and 112 beyond a predetermined amount. Theload which can be held in compression is substantially greater than theload which can be held in tension. This is because the coils grip moreeffectively in one direction than the other. A reversal of threading140, nut threading, or the coil hand directions would provide a devicewhich would hold greater loads in tension than in compression.

One end of coil brake 158 terminates in an axial projection or tang 160which is adapted to be received by slot 162 in base portion 116. Theother end of the coil brake terminates in a squared end 164. Coil brake158 is wound so as to have an inside diameter which is normally slightlyless than the diameter of the drum 144 so that when it is placed on thedrum, there exists frictional gripping engagement therebetween. With thetang 160 restrained from rotation by reason of its posi tion in slot162, it will be obvious that rotation of screw 138 andd rum 144 ineither direction is resisted.

The relationship of brake 158 on drum 144 is clearly shown in FIGURE 3.Whenever the drum is rotated in a counterclockwise direction, as viewedfrom the right end of FIGURE 1 or 3, the helical coil 158 tends to windtighter onto drum 144 thereby resulting in a greater holding or grippingaction, Conversely, rotation of drum 144 in a clockwise direction tendsto unwind coil brake 158 from the drum to thereby permit rotation of thedrum by a lesser force. This is caused by the rotation of the drumacting to unwrap the coils to thereby increase their internal diameter.

The inherent resiliency or gripping action of coil brake 158 tends toprevent rotation of drum 144 in either direction below a predeterminedfigure. This restraint is lowest when the drum is rotating in adirection opposite to the coil hand of brake 158. That is, the coil isless effective in preventing the drum from rotating in theaforementioned clockwise direction. The gripping action of the coilcaused by the drum rotation in a counterclockwise direction isconsiderably increased. Rotation of rod 138 is caused by axial forcesaction through the relatively steep threads on rod 138 and nut 142. Itis apparent from the arrangement described that the positionretainingdevice is adapted to hold a greater load in one axial direction than inthe other.

Release means designated generally by the numeral 166 includes acylindrical shank portion 168 which is rotatably received through acylindrical opening 170 in member 110. The outer end of shank 168 isadapted for receiving a laterally extending handle 172 for manualcontrol of the release means. Shank 168 terminates at its inner end inan enlarged head 174 which is provided with a tangentially directed faceportion 176 for cooperation with squared end 164 of the coil of brake158. Manual rotation of the release means to urge face 176 against end164 expands coil brake 158 to thereby release the gripping or holdingaction of the coil on drum 144. By this maneuver, the drum and screw arefree for rotation in either direction thereby permitting readjustment ofmembers 110 and 112 in either axial direction. It is obvious thatrelative longitudinal movement of these members is controlled by manualmovement of the positionable seat back or by a compression spring(described below), or both.

Helical compression spring 184 is coaxially disposed around members and112 and is anchored at one end against radial shoulder 178 of portion118 and at the other end against washer 180 which is fixed by pins orother means 182 on member 112. Whenever coil brake 158 is released fromnormal gripping action on drum 144, the strentgh of spring 184 issufiicient to urge the positionretaining device (members 110 and 112) toa relatively extended position. When coil brake 158 is gripping drum144, the action of compression spring 184 alone is not suflicient toextend the members. However, the normal force applied by spring 184,when supplemented by a manual pull on the positionable seat back, issufficient to overcome the holding action of coil brake 158 in onedirection. The gripping action of brake 158 is suflicient to preventrotation of rod 138 in response to axial compression between members 110and 112 directed through nut 142.

The arrangement of FIGURE 2 varies from that of FIGURE 1 by reason of arubber washer 137 being provided between Teflon washer 135 and shoulder133. Bushing is provided in base 116 and establishes the bearing forshaft portion 136 which rotates therein. Since a ball bearing is notprovided in this arrangement, the facing shoulders between base 116 anddrum 144 are square so as to present complementary flat surfaces towardone another, The underneath surface of drum 144 is polished for movingcontact with Teflon washer 135.

The arrangement disclosed in FIGURE 2 shows a pair of Teflon washers foreffective action in either direction. Washer 152 (also washer of FIGURE2) is provided in a bearing relationship. It has been found that thepresence of such a washer between flange and member 118 provides anarrangement whereby free rotation therebetween is substantially retardedso that the relative rotation remains substantially constant in responseto axial forces between the first and second members, as for example theforce supplied by a seat occupant. The speed at which rod 138 ispermitted to rotate relative to the inserted washer appears to havelittle, if any, relationship with the load carried between the first andsecond members 110, 112.

The dampening eflect characteristic of the metal to Teflon washersprevents sudden start or movement of the seat back. In other words, itsimulates hydraulic action but eliminates the many undesirablecharacteristics of a hydraulic system.

The structure of FIGURE 1 provides for impeding movement on rod 138 toslow rotation preferably in substantially one axial direction of forcesbetween members 110, 112; however, it is effective in the otherdirection as well. The structure of FIGURE 2 provides for dampening orimpeded movement of these members equally in either direction.

When handle 172 is manually manipulated to expand coil brake 158, rod138 is thereby released for rotation. Spring 184 is then, by itself,sufficient to move members 110, 112 to an extended position. Themovement will be slow by reason of the action of the previouslydescribed Teflon washer. The action just described will move seat backforward to an upright position. As long as brake 158 remains expanded,the seat occupant may move back 190 to any desired position. In anyevent, such movement will be slowed by reasons explained above. Thisslowed movement is desired because it simulates hydraulic restraint. Itwill be appreciated that the effect of the washer is substantially thesame throughout the stroke of the movable members, and is not dependenton the degree of extension or contraction.

Under normal operating conditions, the position-retaining device 100holds positionable back 190 from movemerit rearwardly against relativelygreat loads; however, the holding action may be overcome by a lesserforce directed to move the back rest forward. Whenever handle 172 ismanipulated to release brake 158, back 190 may be moved forwardly orrearwardly with relative ease. Movement in either direction is alwayscushioned by reason of the Teflon washers which provide passiverestraint.

Having thus described my invention, it is obvious that variousmodifications may be made in the same without departing from the spiritof the invention; and, therefore, I do not wish to be understood aslimiting myself to the exact forms, construction, arrangements andcombinations of parts herein shown and described.

I claim:

1. A mechanical position-retaining device for a chair having apositionable back comprising in combination;

a first member having means for attachment to a chair base,

a second member rectilinearly movable relative to the first member andhaving means for attachment to a back positionable with respect to saidchair base,

one of said members having a fixed threaded part and the other of saidmembers rotatably carrying a part having threading for cooperation withsaid fixed threaded part,

said threading being relatively steep so that an axial force applied bysaid back rectilinearly between said first member and said second membertends to rotate said rotatable part,

brake means cooperable with a portion of said rotatable part andselectively engageable therewith to prevent rotation thereof and toprevent relative rectilinear movement of said first and second membersresponsive to an axial load applied by said positionable back,

a member disposed in load carrying relationship between said rotatablepart and said other member,

said member having frictional characteristics such that rotation remainssubstantially constant in response to varying axial loads when saidbrake means is disengaged.

2. A mechanical position-retaining device for a chair having apositionable back comprising in combination;

a first member having means for attachment to a chair base,

a second member rectilinearly movable relative to the first member andhaving means for attachment to a back positionable with respect to saidchair base,

one of said members having a fixed threaded part and the other of saidmembers rotatably carrying a part having threading for cooperation withsaid fixed threaded part,

said threading being relatively steep so that an axial force applied bysaid back rectilinearly between said first member and said second membertends to rotate said rotatable threaded part and move said membersrelative to each other,

brake means comprising a helical resilient member encircling a portionof said rotatable part and selectively engageable therewith to preventrotation thereof and to prevent relative rectilinear movement of saidfirst and second members responsive to an axial load applied to saidmembers,

and means disposed between said rotatable part and said other member inaxial load carrying relationship therewith and having frictionalcharacteristics such that said rotation remains substantially constantin response to varying axial loads when said brake means is at leastpartially released to control the rate at which said members moverectilinearly relative to each other.

3. A mechanical position-retaining device for a chair having apositionable back comprising in combination;

a first member having means for attachment to a chair base,

a second member rectilinearly movable relative to the first member andhaving means for attachment to a back positionable with respect to saidchair base,

one of said members having a fixed threaded part and the other of saidmembers rotatably carrying a rod having threading for cooperation withsaid fixed threaded part,

said threading being relatively steep so that an axial force applied bysaid back rectilinearly between said first member and said second membertends to rotate said rotatable rod,

brake means cooperable with a portion of said rotatable rod andselectively engageable therewith to prevent rotation thereof and toprevent relative rectilinear movement of said first and second membersresponsive to an axial load applied by said positionable back,

and a polytetrafluoroethylene member disposed between said rotatable rodand said other member in load carrying relationship therewith and havingfrictional characteristics such that rotation of said rod remainssubstantially constant in response to varying axial loads when saidbrake means is disengaged.

References Cited UNITED STATES PATENTS OTHER REFERENCES Twiss et al.:Friction of Polytetrafiuoroethylene Dry Bearings, in LubricationEngineering, pp. 255-260, June DAVID J. WILLIAMOWSKY, Primary Examiner.

G. O. FINCH, Assistant Examiner.

1. A MECHANICAL POSITION-RETAINING DEVICE FOR A CHAIR HAVING APOSITIONABLE BACK COMPRISING IN COMBINATION; A FIRST MEMBER HAVING MEANSFOR ATTATCHMENT TO A CHAIR BASE, A SECOND MEMBER RECTILINEARLY MOVABLERELATIVE TO THE FIRST MEMBER AND HAVING MEANS FOR ATTACHMENT TO A BACKPOSITIONABLE WITH RESPECT TO SAID CHAIR BASE, ONE OF SAID MEMBERS HAVINGA FIXED THREADED PART AND THE OTHER OF SAID MEMBERS ROTATABLY CARRYING APART HAVING THREADING FOR COOPERATION WITH SAID FIXED THREADED PART,SAID THREADED BEING RELATIVELY STEEP SO THAT AN AXIAL FORCED APPLIED BYSAID BACK RECILINERALY BETWEEN SAID FIRST MEMBER AND SAID SECOND MEMBERTENDS TO ROTATE SAID ROTATABLE PART, BRAKE MEANS COOPERABLE WITH APORTION OF SAID ROTATABLE PART AND SELECTIVELY ENGAGEABLE THEREWITH TOPREVENT ROTATION THEREOF AND TO PREVENT RELATIVE RECTILINEAR MOVEMENT OFSAID FIRST AND SECOND MEMBERS RESPONSIVE TO AN AXIAL LOAD APPLIED BYSAID POSITIONABLE BACK,